Long wire antenna



Dec. 30, 1941.

LONG WIRE 'ANTENNA Filed Dec. 30', 1939 4 Sheets-Sheet l INVENTORW/LHELM PETERS BY m N ATTORNEY w. PETERS 2,267,945

Deg. 30, 1941. w. PETERS 2,267,945 I LONG WIRE ANTENNA- F'iled Dec. 30,1939 4 Sheets-Sheet 2 Z1 Z2 Z3 9' /s v Z I f) INVENTOR w/ HELY ATTORNEYDec. 30, 1941. w. PETERS LONG WIRE ANTENNA Filed Dec. 30, 1959 4Shets-Sheet ,3

DISTANCE ALONG ANTENNA DISTANCE ALONG ANTENNA \7 j INVENTOR W/LHE'LMPETERS ATTORNEY Dec. 30, 1941. w. PETERS 2,267,945

- LONG WIRE ANTENNA Filed Dec. 30, 1939 4 Sheets-Sheet 4 INVENTORW/LHELM ErsRs" ATTORNEY Patented Dec. 30, 1941 LONG WIRE ANTENNA WilhelmPeters, Berlin, Germany, assignor to Telefunken Gesellschaft fiirDrahtlose Telegraphic in. b. H., Berlin, Germany, a corporation ofGermany Application December 30, 1939, Serial No. 311,862

In Germany October 21, 1938 11 Claims.

In communication with short waves, transmitter antennas and receiverantennas are required which, owing to the variation of the optimumtransmission wave from time to time, must cover a rather wide short waverange, for instance, a range from about 16 to 60 meters. Furthermore,such antennas are required to have a favorable directional effect andfavorable degree of efliciency as regards this effect. Therefore,antennas with tuned dipoles must be excluded for this type of servicesince for a variation of the operating'wave the length of the dipoles ofsuch antennas as well as the relative spacing and the length and phaseof the reflectors thereof would have to be changed within wide limits.But the above stated requirements are favorably complied with by meansof long wire antennas whose length is several wavelengths and which arefed with travelling waves. In fact, on these antennas the waves canappear and propagate in accordance with the length thereof. The greaterthe number of travelling dipoles presented along the length of the wirethe more the direction of the main radiation approaches the direction ofthe axis of the wire. Within a certain range the radiation angle formedwith the main axis remains unchanged and hence, it is not sensitive asregards frequency. Such an outstretched long wire whose length is equalto several wave-lengths therefore produces a conical radiation diagramwhose opening angle changes but slightly with the frequency. Figure 1cshows such a diagram; it is formed from the known diagram of a wire fedwith a standing wave as shown in Figure 1a, wherein the radiationtowards the front and rear is symmetrical, in that the latter isconverted into a travelling wave by adding a wave of same length whichis displaced in space and as regards time at 90, whereby each currentloop dipole of the latter acts as reflector of the former wave, and thusthe radiation diagram of Figure la is to be multiplied with thereflector group characteristic of the cardioid of Figure 1b in order toobtain the Figure 1c. This presentation reveals that in the case oftravelling waves the eifective reflector may be considered as alwaysmoving along at the proper distance and phase with variations of thewavelengths. In this way there is always realized a favorable shieldingtowards the rear. A further advantage of a travelling wave antennaresides in the fact that the transmitter always remains under effectiveload. The effective resistance is equal to the wave resistance for allfrequencies. Since also the radiation angle is almost constant, theresult is that the radiated field strength remains. practically constantwithin a wide frequency range. Now, in

order to obtain from the radiation cone a single resultant pointed ray,two such long wire antennas may be placed with respect to each other inV-form and with opposite polarity and at such an angle that theradiation will be doubled in the direction of the bisector of the angleof the cone. Since the radiation for other directions and larger azimuthangles is extinguished by interference between the radiation from thetwo wires. From the two ray cones of the individual wires only thecommon mutually covered part in the direction of the bisector of theangle remains and is thereby doubled. Now, it is possible to combine twoor a greater number of such V-antennas in the form of a rhombus whichthus radiates a field intensity which is four times that of a singlewire. The radiation power is thus concentrated into a muchsharper cone.

Such long-wire antennas'or antenna systems entail in their known mode ofconstruction serious disadvantages, among other things, a

poor effectiveness and incomplete shielding towards the rear, the firstmentioned disadvantage reducing the effectiveness of such antennas astransmitter antennas while the second disadvantage greatly decreases theefiectiveness of said antennas for receiving. For the production oftravelling waves the end of the antenna facing away from the transmitterand receiver has hitherto been terminated by an ohmic resistance whosevalue is equal to the wave resistance of the line since it was sought torealize the condition for travelling waves on the basis of the theory ofthe telegraph line equation. The wave resistance depends on theproportion between the wire spacing s and diameter d and is calculatedin accordance with the following formulai The said wave resistance isabout 400 to 600 ohms in general. For a radiation resistance of about300 .ohms about one-half of the high frequency energy would be lost inthe terminal resistance. A further disadvantage is the appearance of aback radiation which will be much more appreciable than in the diagramshown in Figure 10.

It is the purpose of the following invention to avoid thesedisadvantages of the travelling wave 2 log antenna thereby improving theantenna. degree of efficiency of the radiation is:

wherein Ia is the input current, Z2. is the input wave resistance, Ie isthe current at the end and Ze is the terminal resistance. From thisfollows that in accordance with the invention the The degree ofefficiency can be considerably improved.

by choosing as low as possible the proportion radiation resistance waveresistance it is necessary to choose the wave resistance as low aspossible. In accordance with the invention this is accomplished byarranging the wires in the form of a cage and by providing connectionsbetween them or arranging them twisted about one another to obtain auniform current distribution.

Figure 2a next shows an ideal long-wire radiator which may have the Waveresistance Z and the uniformly distributed radiation resistance 1 andwhich may be assumed as of infinite length and its associated graphicalillustration of the current distribution along the wire. The beginningof the wire is connected to a high frequency voltage source G. Owing tothe withdrawal of energy through lateral radiation which may be assumedas taking place ideally in a uniform manner across the length, thetravelling current wave will be damped according to an exponential law.In connection with Figure 2b, which is similar to Figure 20., exceptthat the uniformly distributed resistance is assumed to be concentratedin certain equal distances, the above per.- formance can be soconceived, as if through the resistance diffractions would occur in theadvancing wave Inn-1 whereby owing to partial reflexions also rearwardmoving waves are produced which results from the complex resistance.This effect will repeat itself at each joint so that wave trains appearwhich move forwards and backwards. As shown in Figure 1, the latterproduce, however, back radiation thus jeopardizing the shielding of themain wave. If the wave resistance is more and more reduced with constantradiation resistance for obtaining a high degree of efficiency of theradiation, it can be seen from the foregoing considerations that theportion of the standing wave also increases automatically thusjeopardizing the shielding towards the rear. In accordance with theinvention backward moving waves are avoided by varying the waveresistance along the length of the conductor in accordance with thevariation in radiation resistance. The required relation is such thatfor each. element of the radiator the resistances at each joint betweenZnr must be the same in both directions. Since viewed from this placethe resistance r lies in series with Z1i+1, it follows that wherein Znis the wave resistance ahead of the radiation, 1' is the radiationresistance and Zn+1 is the wave resistance in back of the radiation.Then there is:

This law which is not known in the customary antennaswith standingwaves, is a particularity of the antennas with travelling waves anddenotes that the energy entering an antenna elementwill only in part beradiated, and the other part thereof will be transferred refiexion-freefor radiation to the immediately following antenna elements. From thisreasoning it is further seen that a radiation wire with a constant waveresistance also carries waves moving towards the rear when said wireradiates. The necessary condition for this radiation mechanism andtransfer mechanism to operate without reflexion effects, is achieved inaccordance with the present invention by decreasing the wave resistancealong the line. With the assumption of the ideal condition that theradiation resistance alon the line is constant, the wave resistancewould; then have to, be reduced in a linear fashion such as is shown inFigure 20. A comparison; with the current curve of FigureZb shows thatnow reflections no longer occur. Since the terminal resistance is alwaysmatched with the wave resistance at v the end, the result is that forreflection f-ree; operation the terminal resistance is loweraccording tothe inventionso that the efliciency of the radiation will be enhanced.In fact, if Z1 is the resistance of the input waves,v Z'z the terminalresistance and R the totalradiationresistance, then the efiiciency ofthe radiation is For 2 :50 0 0 1 5, and R=40 0 ohms. the arrangementaccording to the invention has a e m n ljresist n e .2.= ;1.R= .0 ohmsndit efilciency'of the: radiation is whereas in the hitherto customaryarrangement the efiiciency degree is only 40%. It is even possible inaccordance with the present invention to reduce the terminal resistancepractically to zero thus obtainingan efiiciency of if in accordance withEquation 3 the input resistance is chosen equal tothe radiationresistance of. the antenna, so that in accordance with, Equation 1 therewill be. 22:0, which means that the antenna is simply shortl-circuitedatthe end. In this ideal case the transmitter feeds energy into the.antenna, in the form of traveling waves. (I .Zi) to the. same extentthat, owingito. its'electromagnetic fields, the. antenna will actuallyradiate (RR). In practice, a low. terminal resistance will-preferably beprovidedsoas to assure certain possibilities of variation. Moreover,under these circumstances the termination in, the arrangement accordingto the, invention need not be carried out exactly with the waveresistance, buta lower resistanceL may be used to, this end since thewave .moving' towards :the rear has hardly any radiation property'owingto the wave resistance being dependent on direction of travel of thewave. The realized-advantage in accordance with the invention resides-in the fact that the matching of the terminal resistances can be chosenwith lesser accuracy.

Actually, the distribution of the radiation along the line is notuniform. But the deliberations so far made remain substantially valid,it being only necessary that the variation of the wave resistance bematched with the distribution of the radiation resistance. Figure 4ashows next for a standing wave the distribution of the radiationresistance along the radiator. It is seen that in accordance with thelateral directional effect the radiation resistance becomes highertowards both sides while it is lowest in the center. In the case of aprogressing wave with unilateral directional radiation according toFigure 10, therefore, in accordance with Figure 4b, the radiationresistance greatly increases towards the end situated in the directionof the radiation. The decrease of the wave resistance must be chosenaccordingly. The Figures a and 51) show examples for the single wireBeverage antenna and for the V-antenna which are dimensioned inaccordance with these requirements. In the case of the rhombus variousradiation wires are connected in parallel for each conductor and spreadapart at the remote end to compensate for a higher radiation resistancefor the sides facing away from the transmitter or receiver. This isshown in the example of Figure 3, as well as in Figure 50. A variationof the wave resistance is herein obtained by the spreading apart of twoparallel connected wires at each side. With constant wave resistancealong the radiation line, in the case of an antenna situated in theopen, the distance between said wires would have to increasesymmetrically towards the center in accordance with a parabola. But dueto the decrease of the wave resistance there results a form according toFigure 50 which will also be affected by the height above ground, sincewith the moving apart of the V-wires the wave resistance will be reducedby the counterinductance of the ground currents. Since, however, inorder to obtain a favorable vertical diagram, the antenna is to bearranged at a rather considerable height above ground, the influence isnot appreciable.

Now, owing to the particularly pronounced variation of the waveresistance the antenna is not readily reversible. It possesses apronounced direction of radiation in the direction of the terminaltransmitter and which is at the same time the most favorable directionof reception for the waves arriving in the opposite direction. In theopposite directions the antenna radiates and receives only at a reducedeifectiveness. Now this dimculty can be overcome in accordance with theinvention by arranging two such antenna systems having oppositedirections and of which at least one or both together can be operatedwith the same or with different programs. This is shown in Figure 5dwherein a pair of superposed rhombic antennas 5| and 52 are connectedthrough double pole double throw switches SW1 and SW2 to a transmitter Gand a terminating resistance R. Thus, either 5| may be connected at theproper ends to the transmitter and resistance for transmission in onedirection, or 52 may be similarly connected for transmission in theother direction. The rhombics are shown as single wires for simplicitybut should be constructed as shown in Figures 3 and 5c.

Figure 6 shows how a plurality of rhombics may be placed in tandem toincrease the directivity without occupying too much space by arrangingthem to substantially overlap.v

- I claim: I

1. A radiating conductor having a length at least equal to several timestheoperating wavelength, a transducer means connected thereto at oneend, said conductor having a wave resistance and a radiation resistanceeach varying along the length of said conductor, said wave resistancedecreasing in proportion to the distance from said one end, while saidradiation resistance increases in proportion to the distance from saidone end. I

2. A radiating conductor having a length at least equal to several timesthe operating wavelength, and having a wave resistance and a radiationresistance each varying along the length of said conductor, a transducermeans connected thereto at one end, said wave resistance decreasing withincreasing distance along the length of said conductor from said oneend, said radiation resistance increasing in proportion to the decreasein wave resistance along said conductor.

3. A radiating conductor having a length at least equal to several timesthe operating wavelength, said conductor having a wave resistance and aradiation resistance each varying along its length, a transducer meansconnected thereto at one end, said wave resistance constantly decreasingwith increasing distance from said one end, said radiation resistancevarying inversely with respect to said wave resistance.

4. A V antenna comprising a pair of conductors as set forth in claim 2.

5. An antenna comprising a pair of conductors as set forth in claim 3,said conductors being arranged in a generally diamond-shaped plan.

6. A bi-directional antenna comprising two pairs of conductors as setforth in claim 3, each pair of said conductors being arranged in agenerally diamond-shaped plan, the conductors of one pair beingoppositely arranged to the other pair.

7. A bi-directional antenna comprising two pairs of conductors as setforth in claim 3, each pair of said conductors being arranged in agenerally diamond-shaped plan, the conductors of one pair beingoppositely arranged to the other pair. said pairs of conductors beingarranged one immediately above the other.

8. A radiating conductor having a length at least equal to several timesthe operating wavelength, said conductor having a wave resistance and aradiation resistance each varying along its length, a transducer meansconnected thereto at one end, said wave resistance constantly decreasingwith increasing distance from said one end, said radiation resistancevarying inversely with respect to said wave resistance, the other end ofsaid conductor being directly connected to ground atits other end.

9. A V-antenna comprising a pair of conductors as set forth in claim 2,said conductors being connected to ground at their other ends through alow resistance connection.

10. A bi-directional antenna comprising two pairs of conductors as setforth in claim 3, each pair of said conductors being arranged in agenerally diamond-shaped plan, the conductors of one pair beingoppositely arranged to the other said transducer, means being, equal. tothe radiation-.reslstanceoi said: conductor at said one end, said;conductor having a constantly decreasing wave resistance toward its.other end where it is 5 connected: to ground.

PETERS.

